Project Summary/Abstract Of the 150,000 patients annually undergoing coronary artery bypass grafting surgery, 35% develop complications that increase mortality 5-fold and expenditures by 50%. Differences in patient risk and operative approach explain only 2% of hospital variation in some complications. The intraoperative phase remains understudied as a source of variation, despite its complexity and amenability to improvement. Unfortunately, little is known about the multitude of factors impacting optimal cardiac surgical outcomes. Within non-cardiac surgery, peer rater assessments of a surgeon?s technical skills (e.g., instrument handling) are correlated with complications. Beyond technical skills, the cardiac surgical team uniquely relies on carefully orchestrated non-technical practices (e.g., teamwork, communication, situational awareness, leadership) to deliver care, including ensuring the patient?s hemodynamic stability across phase transitions involving extracorporeal cardiopulmonary bypass. Most research to date has focused on technical skills and non- technical practices in simulated environments with subjective human raters, thus lacking the medical and psychological fidelity of real-world surgery required to identify relevant improvement targets. High-dimensional computer-based assessments of video recordings, including capabilities for recognizing and tracking human activity (video understanding), may offer unparalleled capabilities for providing an objective, non-simulation- based platform for assessing technical skills and non-technical practices of surgical outcomes. Our long-term goal is to reduce surgical complications by identifying and promoting adoption of evidence- based surgical practices. The objectives of this proposal are to: (i) investigate the relationship between peer rater assessments of intraoperative technical skills and non-technical practices with risk-adjusted complication rates and (ii) to evaluate the feasibility of automating computer-based assessments to identify important intraoperative technical skills and non-technical practices. This multi-center study leverages two mature physician collaboratives providing detailed intraoperative data merged with The Society of Thoracic Surgeons outcomes data. We have the following aims: (1) To investigate the relationship between peer rater assessments of surgeon technical skills and variability in risk-adjusted patient complications; (2) To investigate the relationship between peer rater assessments of intraoperative team-based non-technical practices and variability in risk-adjusted patient complications; (3) To explore the feasibility of using objective, data-driven computer-based assessments to automate the identification and tracking of significant, intraoperative determinants of risk-adjusted patient complications. This study, which aligns with NHLBI?s priorities by leveraging a multidisciplinary team to identify modifiable determinants of surgical performance, is expected to positively impact care by using a platform to broadly evaluate surgical outcomes.